2021 EPAC Season

[Category5Kaiju]

The vertical instability issues of this basin rn rival that of 2013.

Oh yeah, a 20 NS season with only one major hurricane (Raymond) that did not obtain that status until late season, let alone only be a Category 3? That was a very weird year for both the EPAC and Atlantic

[aspen]

The quality of storms this season so far can be compared to over recent seasons by looking at the average ACE and ICE (my intensity metric) per storm up until this point in each year. I chose 2017, 2018, 2019, and 2020 for comparison, each being four very different seasons: a cool neutral ENSO, an El Niño year with record-breaking ACE, a weak Niño with a generally favored Atlantic, and a La Niña with a heavily favored Atlantic.

So far, 2021 has produced 11 named storms, with an average ICE of 16.56 units per system. Felicia dominates the season’s total of 182.21 units so far.

As of August 9th, 2017, the EPac was up to TD-11E (tropical depressions still count towards the ICE total unless they have winds of 25 kt and/or a pressure of 1015 mbar). The average ICE per storm was 24.13 units, and the season ended with 461.66 units, about 1.19x the 1977-2017 Atlantic mean. It was a respectable season but nothing crazy.

As of August 9th, 2018, several storms were active or had just dissipated. The basin was also up to its K storm and was at 34.21 ICE/storm. This is the highest of the seasons I picked, but I’m surprised it was that low due to all the hurricanes by this point (Aletta, Bud, Fabio, and Hector). 2018 went on to have the highest ACE of any EPac system due to an insane number of long-tracking Cat 4/5s, and finished with a huge ICE total of 1,337.94 units.

As of August 9th, 2019, the basin was only up to Gil. Both ACE and ICE were dominated by borderline Cat 5 Barbara and Cat 4 Erick, with lots of weak development. Both storms, especially Barbara, helped get the season’s ICE/storm by this point to 30.66 units. The season ended as a similarly “eh” year like 2017 with a total of 464.41 units of ICE.

As of August 9th, 2020, TS Elida was currently active, but since it had not reached peak intensity yet, it is not counted in my calculations. The ACE per storm at this point was only 11.47 units; it was ridiculous how many depressions were failing to even become named storms, and how pathetic most storms were. The average ICE/storm by 8/9/20 was entirely carried by Cat 4 Douglas, which was responsible for >85% of the ICE. We all know how unimpressive 2020 was. It ended with 339.32 units of ICE, only 88% the 1977-2017 Atlantic mean.

In summary: 2021 is essentially just a slightly less garbage version of 2020, with both seasons being carried by a single Cat 4 and having most of their storms struggle with shear and stability brought on by a developing La Niña.

The ICE formula is:

([1015-pressure] x [winds-25])/72.5

[storminabox]

The quality of storms this season so far can be compared to over recent seasons by looking at the average ACE and ICE (my intensity metric) per storm up until this point in each year. I chose 2017, 2018, 2019, and 2020 for comparison, each being four very different seasons: a cool neutral ENSO, an El Niño year with record-breaking ACE, a weak Niño with a generally favored Atlantic, and a La Niña with a heavily favored Atlantic.

So far, 2021 has produced 11 named storms, with an average ICE of 16.56 units per system. Felicia dominates the season’s total of 182.21 units so far.

As of August 9th, 2017, the EPac was up to TD-11E (tropical depressions still count towards the ICE total unless they have winds of 25 kt and/or a pressure of 1015 mbar). The average ICE per storm was 24.13 units, and the season ended with 461.66 units, about 1.19x the 1977-2017 Atlantic mean. It was a respectable season but nothing crazy.

As of August 9th, 2018, several storms were active or had just dissipated. The basin was also up to its K storm and was at 34.21 ICE/storm. This is the highest of the seasons I picked, but I’m surprised it was that low due to all the hurricanes by this point (Aletta, Bud, Fabio, and Hector). 2018 went on to have the highest ACE of any EPac system due to an insane number of long-tracking Cat 4/5s, and finished with a huge ICE total of 1,337.94 units.

As of August 9th, 2019, the basin was only up to Gil. Both ACE and ICE were dominated by borderline Cat 5 Barbara and Cat 4 Erick, with lots of weak development. Both storms, especially Barbara, helped get the season’s ICE/storm by this point to 30.66 units. The season ended as a similarly “eh” year like 2017 with a total of 464.41 units of ICE.

As of August 9th, 2020, TS Elida was currently active, but since it had not reached peak intensity yet, it is not counted in my calculations. The ACE per storm at this point was only 11.47 units; it was ridiculous how many depressions were failing to even become named storms, and how pathetic most storms were. The average ICE/storm by 8/9/20 was entirely carried by Cat 4 Douglas, which was responsible for >85% of the ICE. We all know how unimpressive 2020 was. It ended with 339.32 units of ICE, only 88% the 1977-2017 Atlantic mean.

In summary: 2021 is essentially just a slightly less garbage version of 2020, with both seasons being carried by a single Cat 4 and having most of their storms struggle with shear and stability brought on by a developing La Niña.

The ICE formula is:

([1015-pressure] x [winds-25])/72.5

Great post man. After three relatively down years in EPAC, I wonder if we will see a busier season in 2022.

[Kingarabian]

Fortunately for us all, the 18z GFS has even more slop.

[Category5Kaiju]

Fortunately for us all, the 18z GFS has even more slop.

It only shows up to Marty within the next 16 days. GFS has definitely turned cold against the EPAC

[Kingarabian]

Fortunately for us all, the 18z GFS has even more slop.

It only shows up to Marty within the next 16 days. GFS has definitely turned cold against the EPAC

Marty and Nora on the 18z GFS. Super weak Marty though.

[Yellow Evan]

The vertical instability issues of this basin rn rival that of 2013.

2013:



2021:



2015:

[Kingarabian]

The vertical instability issues of this basin rn rival that of 2013.

2013:

https://i.imgur.com/8xfQJAk.gif

2021:

https://i.imgur.com/zrH164B.gif

2015:

https://i.imgur.com/YYf7sc2.gif

I think the methodology in regards to these graphs is broken. There's simply no way instability is this low despite the overall lack of quality.

[Category5Kaiju]

The vertical instability issues of this basin rn rival that of 2013.

2013:

https://i.imgur.com/8xfQJAk.gif

2021:

https://i.imgur.com/zrH164B.gif

2015:

https://i.imgur.com/YYf7sc2.gif

I think the methodology in regards to these graphs is broken. There's simply no way instability is this low despite the overall lack of quality.

I would have to agree; just like the instability graph with the Atlantic being constantly off, for us to still get hurricanes and one major hurricane in the EPAC I would have to imagine otherwise

[weeniepatrol]

"NE Pacific" is in fact a huge, seemingly-arbitrarily chosen region that is not reflective or indicative of what people think it means, as tropical cyclone trackers uninterested in stability (or other tropical cyclone related parameters) over the entire western US and poleward of 40N.

[Yellow Evan]

I’ve been following that vertical instability product for years in the basin. It seems to be a good indicator of a quality or quantity season though I can’t give a deep dive into why because I don’t know how it’s derived from. It does overall match the lowly activity we’ve seen this year, with our lone major hurricane coinciding a spike in instability.

[Kingarabian]

I’ve been following that vertical instability product for years in the basin. It seems to be a good indicator of a quality or quantity season though I can’t give a deep dive into why because I don’t know how it’s derived from. It does overall match the lowly activity we’ve seen this year, with our lone major hurricane coinciding a spike in instability.

But that graphic shouldn't be spiking only when there's a major hurricane. 12 TC's most of them healthy TS's low end hurricanes isn't a sign of low instability. The month long phase of the Atlantic pre PT6 would be a good sign of stability and low instability vs what the EPAC has been doing.

[Yellow Evan]

I’ve been following that vertical instability product for years in the basin. It seems to be a good indicator of a quality or quantity season though I can’t give a deep dive into why because I don’t know how it’s derived from. It does overall match the lowly activity we’ve seen this year, with our lone major hurricane coinciding a spike in instability.

But that graphic shouldn't be spiking only when there's a major hurricane. 12 TC's most of them healthy TS's low end hurricanes isn't a sign of low instability. The month long phase of the Atlantic pre PT6 would be a good sign of stability and low instability vs what the EPAC has been doing.

I mean it isn’t hard to imagine why a tropical storm might be more stable than a Category 4 hurricane and I do think this metric has correlated well with quality versus quantity seasons so I’m inclined to think there is value here. But beyond that, there are unresolved questions.

[Kingarabian]

I’ve been following that vertical instability product for years in the basin. It seems to be a good indicator of a quality or quantity season though I can’t give a deep dive into why because I don’t know how it’s derived from. It does overall match the lowly activity we’ve seen this year, with our lone major hurricane coinciding a spike in instability.

But that graphic shouldn't be spiking only when there's a major hurricane. 12 TC's most of them healthy TS's low end hurricanes isn't a sign of low instability. The month long phase of the Atlantic pre PT6 would be a good sign of stability and low instability vs what the EPAC has been doing.

I mean it isn’t hard to imagine why a tropical storm might be more stable than a Category 4 hurricane and I do think this metric has correlated well with quality versus quantity seasons so I’m inclined to think there is value here. But beyond that, there are unresolved questions.

Thunderstorms are a great form of atmospheric instability though. The EPAC region near Mexico has to be instable right now. Because other than Hilda, TS Kevin so far far has had the long period of coldest convection tops of any storm this season. Regardless if it was vertically stacked or not, it was shooting out very cold tops. The EPAC in general has looked convective active this season. Maybe the area west of California and the entire WCONUS is bringing the graph down. But I don't know why they would factor instability over the WCONUS states in something that's supposed to measured over the tropics.

[Yellow Evan]

But that graphic shouldn't be spiking only when there's a major hurricane. 12 TC's most of them healthy TS's low end hurricanes isn't a sign of low instability. The month long phase of the Atlantic pre PT6 would be a good sign of stability and low instability vs what the EPAC has been doing.

I mean it isn’t hard to imagine why a tropical storm might be more stable than a Category 4 hurricane and I do think this metric has correlated well with quality versus quantity seasons so I’m inclined to think there is value here. But beyond that, there are unresolved questions.

Thunderstorms are a great form of atmospheric instability though. The EPAC region near Mexico has to be instable right now. Because other than Hilda, TS Kevin so far far has had the long period of coldest convection tops of any storm this season. Regardless if it was vertically stacked or not, it was shooting out very cold tops. The EPAC in general has looked convective active this season. Maybe the area west of California and the entire WCONUS is bringing the graph down. But I don't know why they would factor instability over the WCONUS states in something that's supposed to measured over the tropics.

It’s possible Kevin/Hilda/other TC’s have had little affect because the calculated area is so large. There’s also not a full one to one link between cloud top temperature to vertical instability.

THDV: The average vertical instability parameter, defined as the vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment.

[Kingarabian]

12z CMC and Euro have Marty in about 8-10 days.

[gatorcane]

The EPAC is looking rather quiet now on the GFS in the long-range, Atlantic looks to be up next…

[Kingarabian]

00z GFS goes up to Nora through 16 days.
00z CMC and Euro shows Marty within 8 days.

[Yellow Evan]

EPS trending towards a break in the sinking motion in late August.

[Kingarabian]

https://cdn.discordapp.com/attachments/733552978572869632/875028004223471696/eps_chi200_anomaly_hov_equatorial_2021080900_MEAN.png

EPS trending towards a break in the sinking motion in late August.

Yeah that's probably the reflection of Marty, which is now gaining pretty good support for development by days 8-10 since it'll have help from a passing CCKW.